Bacteria communicate with one another using chemical signal molecules that can be small hormone-like molecules, sometimes called autoinducers. The information supplied by these chemical signal molecules is critical for synchronizing the activities of large groups of bacterial cells. This chemical communication involves producing, releasing, detecting, and responding to the small hormone-like molecules, or autoinducers. This process is termed quorum sensing, and it allows bacteria to monitor the environment for other bacteria and to alter behavior on a population-wide scale in response to changes in the number and/or species present in a community. Most quorumsensing-controlled processes are beneficial when carried out simultaneously by a large number of cells. Thus, inhibition of quorumsensing can disrupt the health of a bacterial community, and if the bacteria are pathogenic or responsible for infection, inhibition of quorumsensing can have therapeutic, anti-bacterial value.
Members of the bacterial genus Streptococcus are responsible for causing a wide variety of infections in humans. Many Streptococci use quorum-sensing systems to regulate several physiological properties, including the ability to incorporate foreign DNA, tolerate acid, form biofilms, and become virulent. Biofilms, such as dental plaque, are dense aggregates of surface-adherent microorganisms embedded in an exopolysaccharide matrix.